Hi All,

I have build a circuit using crocodile clips, and I have used a JK Flip Flop, however, my local electronics store only sells a Dual JK flip-flop.

I have the following circuit, to what pins do I need solder to make this circuit still work ops:

The flip flop i can buy:
http://www1.jaycar.com.au/images_uploaded/CD4027BC.PDF

Now with the attached circuit, when I pulse 5v+ at point A, the red LED comes on and stays on. If I pulse 5v+ at B, the red LED turns off, and the green LED turns on. This is all i'm trying to acheive so if theres an easier way please let me know, but I'd like to work this out as well

Thanks all in advance, :wink:

Tim.

Attached Images

jkflipflop.jpg (4.4 KB, 627 views)

 

In your circuit:
J = pin 10
k = pin 11
s= pin 9
r= pin 12
q= pin 15
q(bar)= pin 14
pin 16 = +voltage
pin 8 = gnd

Thats the relationship between the circuit and the FF.
however, all you are using is the set and reset, of the FF, you dont even need to connect j and k to the circuit.

__________________
Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

ok if you connect the ckt as shown it should work fine.

no connection is needed to J or K inputs.

Attached Images

001.jpg (6.7 KB, 604 views)

 

The other circuit is known as Bistable Multivibrator which uses switching
Transistors for doing the same thing.In place of jk SR flip Flop can also be used.However Digital circuits are easy to manage.

 

Hmm well I couldn't get it to work properly (or at all) I wonder if I have blown it up..

I put about 14.4 volts to pin 16, and 5v regulated to pins 9 and 12 alternatevly and the LED from pin 14/15 did not light up.

No biggie if I've blown it up but is there an easier/cheaper way to do this or should I use the same circuit just a different way.

Thanks in advance,

Tim.

P.S: Can relays work from 12v- as well as 12v+??

 

Looking at the datasheet, you shouldn't have hurt it.
pin 16 can go from -.5V to +18V (max) and then the input pins can range anywhere between 0V and the voltage on pin 16.

What sise resistors did you use for the leds? Even though you put 14.4V on pin 16, the voltage coming out of the output pins is only 5V (I think).

__________________
Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

they had 470ohm on them, changed to 360 and they can both be seen on very dimly, unless I put either the S or R pins to 5v then the both go bright..

Any ideas?

 

Both LED's turn on when you bring just one of the inputs high?

I looked at the datasheet again, I think it says that if you are running Vdd (pin 16) at 15V, then your High level input has to be at least 11V, and the low level input has to be below 4V.
maybe try connecting pin 16 to your +5V supply?

__________________
Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

hmm but i don't have a constant 5v+ supply

Should I bypass the voltage regulators and pump 12v into the inputs??

 

why cant you just use your +5 regulated supply on it?

__________________
Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

A 40-series can handle up to 15V supply, so it shouldn't be damaged.
But the input voltage levels for a logic 0 and 1 are dependant on the supply voltage. If you feed it 15V (14.4) then a logic 1 starts from 11V and higher. applying 5V to an input will be considered a logic 0.

Also check the maximum output current for the family (CD) you want to use. Most 40- families don't like drivingleds directly... (they will do it but die an early death by doing so)...

Depends on the relay, does it have a + and - input then no, if it hasnt then yes...

 

Well the relays are just standard automotive relays, I was hoping to use them with my power windows, which have 12v- to the motor on the way down..

As for the flip flop, the specs are in the link in my first post.. I'm probably going to have to go out and buy all the bits again, so if I need transistors etc can someone make a schematic with everything I should use??

Thanks in advance,

Tim.

 

So the -12V will go trough the contacts? I assumed it was to feed the coil.
In that case there's no problem at all, the contacts are just mechanical switches, they don't care about + and -

I need more info to draw you a scematic. What voltage will you be feeding the 4027 from (14.4?, or do you have 5v available?). Is this a clean regulated power supply? Where do the input signals come from? (a switch, or another circuit?).

 

Ok well what happens, is when I arm my car alarm, it pulses the 12v+ out 2 wires, 1 for lock and one for unlock. What I am planning on doing id making the alarm cut the ACC and ON wire, and also after the cut in the on wire I am putting in a turbo timer, hence my timer post in the Electronics Design/Reviews area..

I also want some form of visual indication if the flip flop is on armed or disarmed status

I eventually want to build into the circuit something which when you lock the car, the first pulse will cut the ACC and ON (with turbo timer extension) and start to put the power windows up (if someone is hanging out the window its their own fault), then, if I pulse the lock wire again (by pressing the lock button again) it will stop the power windows going up.

Unlock once will resume the ACC and ON circuits, and the second unlock pulse will roll the windows down.

I know this sounds hard but i have been working on a crocodile clips circuit and it so far is going to plan, I've just moved over to using large capacitors instead of 555 timers.. saves me a bit of money.

Thanks all who can help with circuits/links etc.

Tim.

edit: I have 12v+ avaiable most of the time, the engine will hit about 14.4v when running (max) so I have just boght 3 12v+ voltage regulators.
I will e using these 12v+ as my sources. Thanks!

 

14 posts in this thread to find out what u actually wanted to do !!!